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000
FXUS63 KMPX 190200
AFDMPX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN
900 PM CDT SAT MAY 18 2013

.UPDATE...

00Z AVIATION DISCUSSION ADDED BELOW.

&&

.SHORT TERM...(THIS EVENING THROUGH SUNDAY)
ISSUED AT 312 PM CDT SAT MAY 18 2013

THE HYDROLOGIC ISSUES FOR TONIGHT AND SUNDAY ARE DISCUSSED IN A
SEPARATE SECTION BELOW. CONVECTION IS EXPECTED TO DEVELOP LATE
THIS AFTERNOON ACROSS WEST CENTRAL MN AND PROPAGATE SLOWLY ENE
THROUGH THE EVENING. MORE CONVECTION IS FORECAST TO EXPLODE OVER
NE/KS AND RACE NE...PERHAPS REACHING SW MN AFTER MIDNIGHT AND INTO
CENTRAL...EAST CENTRAL AND SOUTHEAST MN DURING THE LATE NIGHT
HOURS. DEEP LAYER SHEAR IS BEST TONIGHT ACROSS WEST CENTRAL INTO
CENTRAL MN ALONG WITH ML CAPE NEAR 1500 J/KG. DOWNDRAFT CAPE IS
ALREADY NEAR A 1000 J/KG NEAR OUR WESTERN BORDER ATTM. HENCE...A
FEW SEVERE STORMS WITH HAIL AND WIND ARE POSSIBLE.

SUNDAY SHOULD BEGIN WITH CONVECTION ACROSS CENTRAL AND EASTERN MN
WHICH WILL WEAKEN/DISSIPATE WHILE MOVING NE THROUGH THE LATE
MORNING HOURS. THERE MAY BE A FEW HOURS DURING THE LATE MORNING
AND EARLY AFTERNOON WITH SOME SUNSHINE AND LITTLE CONVECTION
OCCURRING. THAT IS LIKELY TO CHANGE DURING THE MID TO LATE
AFTERNOON HOURS WITH CLUSTERS OF STRONG TO SEVERE STORMS
DEVELOPING ACROSS CENTRAL AND SOUTHERN MN AND BY EVENING ACROSS
WEST CENTRAL WI. MODEL CONSENSUS IS FOR 1500-2000 J/KG OF CAPE
WITH NEARLY 500 J/KG BEING HAIL CAPE. DEEP LAYER SHEAR IS BEST
(30-40 KNOTS) ACROSS SOUTHERN MN INTO WEST CENTRAL WI DURING THE
LATE AFTERNOON AND EVENING. HOWEVER...0-1KM SHEAR INCREASES TO
NEAR 25 KNOTS ACROSS CENTRAL MN WITH SFC-3KM CAPE OVER 150 J/KG
ALONG AND SOUTH OF THE AFOREMENTIONED BOUNDARY. THIS WILL NEED TO
BE WATCHED FOR POSSIBLE TORNADIC DEVELOPMENT.

.LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY)
ISSUED AT 312 PM CDT SAT MAY 18 2013

THE LONG TERM FORECAST REMAINS QUITE WET INTO THURSDAY AS A
VERTICALLY STACKED LOW PRESSURE SYSTEM OVER THE NORTHERN AND
CENTRAL PLAINS BEGINS A SLOW EASTWARD DRIFT. THUNDERSTORMS WILL
WANE SUNDAY NIGHT WHILE MOVING NE. HOWEVER...MONDAY REMAINS A DAY
OF INTEREST FOR MORE SEVERE WEATHER OVER OUR EASTERN FA. AN
OCCLUDED FRONT WILL LIFT NORTHEAST ACROSS EASTERN MN AND WEST
CENTRAL WI DURING THE DAY. CAPE AND SHEAR VALUES ARE RESPECTABLE
BY AFTERNOON FROM THE TWIN CITIES ON EAST AND SOUTH AND A FEW MORE
SEVERE STORMS ARE POSSIBLE. THERE REMAINS A SMALL CHANCE FOR
THUNDER TUESDAY AND WEDNESDAY...DEPENDING ON HOW FAST THE
VERTICALLY STACKED LOW PRESSURE SYSTEM MOVES. RIGHT NOW...THERE
CONTINUES TO BE A SLOWING TREND. HENCE...WE WILL BE DEALING WITH
RATHER HIGH POPS THROUGH MID WEEK.

THE GFS AND EC SHOW THIS LOW PRESSURE SYSTEM BREAKING DOWN ACROSS
THE REGION ON THURSDAY WITH HIGH PRESSURE FOR FRIDAY AND PERHAPS
SATURDAY BEFORE YET ANOTHER LARGE UPPER TROUGH MOVES INTO THE
WESTERN THIRD OF THE NATION...SPREADING MORE SHOWERS BACK. THE
WARMEST DAY IN THE EXTENDED RANGE IS ON MONDAY WITH HIGHS IN THE
50S AND 60S FOR TUESDAY AND WEDNESDAY WITH 60S TO LOWER 70S FOR
FRIDAY AND SATURDAY.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING)
ISSUED AT 859 CDT SAT MAY 18 2013

UNCERTAINTY RULES THE DAY IN THESE TAFS AS A FEW ROUNDS OF SHOWERS
AND THUNDERSTORMS WILL BE POSSIBLE. THIS EVENING...STORMS HAVE
INITIATED IN WRN MN ALONG A STATIONARY FRONT THAT STRETCHES EAST
ACROSS CENTRAL MN INTO NW WI. BASED ON MEMBERS 1 AND 3 OF THE
HOPWRF...EXPECT THESE CELLS TO REMAIN CONFINED TO NEAR THEIR
CURRENT LOCATION DUE TO WEAK STEERING FLOW AND SLOWLY DISSIPATE
AFTER SUNSET. ATTENTION THEN TURNS TO LINE OF BKN STORMS FROM
SODAK ALL THE WAY DOWN TO KS AS IT PUSHES EAST OVERNIGHT. TIMED
THIS NEXT BATCH OF SHRA/TSRA IN OFF THE HRRR...THOUGH IT IS
RUNNING A FEW HOURS FASTER THAN THE HOPWRF. NOTICED THE 22Z
VERSION OF THE HRRR SLOWED THE LINE DOWN SOME AS WELL...SO THE
RETURN OF SHRA/TSRA LATE TONIGHT INTO SUN MORNING MAY NEED TO BE
SLOWED DOWN. SUNDAY MORNING MAY VERY WELL BE SIMILAR TO WHAT WAS
SEEN THIS MORNING WITH CONVECTION THAT MOVED ACROSS THE AREA.
EXPECT MAINLY VFR CIGS THROUGH THE NIGHT...THOUGH WITH RECENT RAIN
AND HIGH DEWPS...MVFR VSBYS IN BR/HZ WILL LIKELY DEVELOP. EXPECT
ANOTHER LULL IN ACTIVITY IN THE LATE MORNING/EARLY AFTERNOON
SUNDAY...BEFORE MORE STORMS DEVELOP MAINLY AFTER 20Z ON SUNDAY.
SOUNDINGS AT ALL TERMINALS ARE MOIST/UNSTABLE AND WEAKLY CAPPED...
SO WILL NOT TAKE MUCH FORCING TO KICK OFF STORMS. GIVEN HIGH
CONFIDENCE IN THUNDERSTORMS OCCURRING TOMORROW...BUT LOW
CONFIDENCE IN TIMING/LOCATION THIS FAR OUT...WENT WITH PROB30
GROUPS FOR TSRA AT ALL TERMINALS SUNDAY AFTERNOON.

KMSP...EXPECT ANY TSRA ACTIVITY THIS EVENING TO REMAIN NEAR OR
NORTH OF THE BOUNDARY SITUATED ACROSS CENTRAL MN. CONFIDENCE IS
HIGH IN ANOTHER ROUND OF MORNING STORMS FOR MSP...THOUGH THERE ARE
TIMING ISSUES WITH IT. 21Z RUN OF THE HRRR HAS STORMS APPROACHING
THE FIELD AT 11Z...WHILE ALL MEMBERS OF THE HOPWRF HAVE THE LINE
WELL WEST OF THE FIELD AT 12Z SUNDAY. HAVE A SOMEWHAT LARGE 10Z TO
16Z WINDOW FOR CONVECTION...BUT DOES LOOK LIKE FOR 2 OR 3 OF THOSE
HOURS...THERE WILL BE TSRA ACTIVITY. FOR SUNDAY AFTERNOON/EVENING...
GIVEN UNSTABLE AND WEAKLY CAPPED ENVIRONMENT...EXPECT WIDESPREAD
TSRA TO DEVELOP AGAIN IN THE AFTERNOON AND LAST INTO SUNDAY
EVENING. STILL PLENTY OF UNCERTAINTY WITH TIMING/PLACEMENT OF
STORMS SUNDAY AFTERNOON...SO HAVE A PROB30 GROUP FOR MOST LIKELY
WINDOW FOR SEEING STORMS AT THIS POINT.

/OUTLOOK FOR KMSP/
MON...VFR/MVFR CIGS. SHRA/TSRA LIKELY. S WIND 10-15 KTS.
TUE...VFR/MVFR CIGS. SHRA/TSRA LIKELY. E-NE WIND 5 KTS.
WED...VFR/MVFR CIGS. SHRA LIKELY. NE WIND 5-10 KTS.

&&

.HYDROLOGY...
ISSUED AT 312 PM CDT SAT MAY 18 2013

A SIGNIFICANT RAINFALL EVENT IS POSSIBLE TONIGHT AND SUNDAY
MORNING ACROSS CENTRAL MN. PW VALUES ARE PROJECTED TO INCREASE TO
OVER 1.50 INCHES TONIGHT ACROSS THE MN FA IN CONCERT WITH A
DEVELOPING LOW LEVEL JET. THE PW VALUES FORECAST ARE BETTER THAN
2 STANDARD DEVIATIONS ABOVE NORMAL AND ARE NEAR RECORD VALUES FOR
THE MONTH OF MAY (1.67). A SPECIAL 16Z KMPX RAOB THIS MORNING ALREADY
HAD PW VALUES AT 1.38 INCHES. WITH THE INCREASE IN MOISTURE
TONIGHT... THERE IS STRONG (925-850MB) FRONTOGENESIS THAT DEVELOPS
ACROSS CENTRAL MN AND REMAINS IN PLACE THROUGH MIDDAY SUNDAY. IN
ADDITION...AN INVERTED SURFACE TROUGH ACROSS CENTRAL SD AND
EASTERN ND IS FORECAST TO DROP SE INTO CENTRAL AND NORTHERN MN
BY SUNDAY MORNING WITH PRETTY STRONG LOW LEVEL CONVERGENCE SHOWN.
VARIOUS WRF MODELS SHOW CONVECTION SPREADING/DEVELOPING ACROSS
CENTRAL MN THIS EVENING WITH TRAINING NOTED. ANOTHER ROUND OF
CONVECTION MAY MOVE IN LATE IN THE NIGHT FROM EASTERN SD AND SW
MN. THE STORMS COULD EASILY PRODUCE 1 TO 2 INCHES OF RAIN PER HOUR
AS THEY MOVE THROUGH...MUCH LIKE THE STORMS LAST NIGHT AND THIS
MORNING OVER PARTS OF THE MN FA. IN FACT...WIDESPREAD 1 TO 3 INCH
RAINS FELL ACROSS CENTRAL MN EARLY THIS MORNING...WHICH HAS
CERTAINLY SOAKED THE GROUND. HENCE...IN COLLABORATION WITH
KDLH...WE ISSUED A FLASH FLOOD WATCH FROM 9 PM THIS EVENING UNTIL
1 PM ON SUNDAY FOR AREAS ALONG AND NORTH OF A LINE FROM MORRIS
THROUGH ST. CLOUD TO CAMBRIDGE.

&&

.MPX WATCHES/WARNINGS/ADVISORIES...
MN...FLASH FLOOD WATCH THROUGH SUNDAY AFTERNOON FOR MNZ041>045-
     047>052.

WI...NONE.
&&

$$

SHORT TERM...RAH
LONG TERM...RAH
AVIATION...MPG
HYDROLOGY...RAH